Wanting to install a small round 2.5" tach on my 2015 Cup. Typically these aftermarket tachs have a green wire that's the sensor or trigger wire. The tach is powered up and properly wired, except it doesn't read rpm. I tried to connect the green wire to the coil ground as suggested for typical installations, but that's not working. I'm sure someone out there has done this, I'm not the only one dissatisfied with the pathetic OEM dash RPM readout.
I know the tach works, or at least functions, because the needle swings up to 10K rpm when I power it up, then swings back to zero.
Do I need to tap into a trigger wire coming out of the ECU? Pull the dash and tap into the wire that actuates the normal RPM display? If so, which wire? The service manual wiring diagram is equally pathetic, doesn't actually identify the connections to the dash- the various parts of the display, like coolant temperature, etc. So if I pull the dash or the ECU I'll have no idea and no way of determining which of those dozens of wires I'm looking for.
I know the tach works, or at least functions, because the needle swings up to 10K rpm when I power it up, then swings back to zero.
Do I need to tap into a trigger wire coming out of the ECU? Pull the dash and tap into the wire that actuates the normal RPM display? If so, which wire? The service manual wiring diagram is equally pathetic, doesn't actually identify the connections to the dash- the various parts of the display, like coolant temperature, etc. So if I pull the dash or the ECU I'll have no idea and no way of determining which of those dozens of wires I'm looking for.